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C Harada

Publications and source records attributed to C Harada.

32 records · Page 2Linked to original sources
PubMed1992

[Electrical tinnitus suppression--a comparative study of clinical trials and animal experiments].

Electrical tinnitus suppressor was newly developed and clinical study of electrical tinnitus suppression was discussed. Tinnitus was treated with this prototype suppressor in 38 ears out of 34 outpatients. Tinnitus was suppressed during electrical stimulation in all patients. After cessation of electrical stimulation, in 5 ears out of them tinnitus has disappeared at least for more than six months. In 12 ears it made tinnitus more than 10 dBHL softer for the following period, about six months. Hearing was unchanged in all patients. To know the mechanism how electrical stimulation of the cochlea suppressed tinnitus, animal experiments using a single fiber recording technique were made. A positive direct current on the cochlea suppressed the spontaneous activity of the cochlear nerve fiber, while a negative direct current increased the spontaneous activity. An alternative current on the cochlea increased the spontaneous activity of the cochlear nerve fiber. These electrical effects on the spontaneous activity were temporary. Therefore, after cessation of electrical stimulation on the cochlea, changed spontaneous activity restored to the level of prestimulation. Comparing temporary electrical effects on the spontaneous activity of cochlear nerve fiber with a longer suppression on tinnitus, tinnitus suppression following electrical stimulation of the cochlea was not thought to occur at the level of cochlea, but at auditory central nervous system.

Action Potentials↗
PubMed1991

[Effects of intravenous injection of salicylate on the spontaneous discharge rate of the cochlear nerve].

This study was aimed to elucidate the effects of salicylate on the cochlear nerve by recording the spontaneous activity in guinea pigs. After guinea pigs were given salicylate (200 mg/kg) intravenously, the transient reduction in cochlear spontaneous activity and the elevation over the subsequent 10-20 minutes were observed in three of four fibers recorded for more than 30 minutes. The mean spontaneous discharge rate of 102 fibers after administration of salicylate (200 mg/kg) was not significantly higher than the control values from 30 to 120 minutes after salicylate administration, while that rate of 112 fibers after administration of salicylate (400 mg/kg) was significantly higher. The observed changes in spontaneous activity due to salicylate administration may represent the evidence of a tinnituslike phenomenon in guinea pigs.

Animals↗
PubMed1990

Spatial properties of vertical eye movement-related neurons in the region of the interstitial nucleus of Cajal in awake cats.

1. Maximal activation directions of vertical burst-tonic and tonic neurons in the region of the interstitial nucleus of Cajal (INC) were examined in alert cats during vertical vestibulo-ocular reflex induced by sinusoidal rotation (at 0.11 Hz +/- 10 deg, or 0.31 Hz +/- 5 deg) in a variety of vertical planes using a null point analysis. The results were compared with the angles of anatomical and functional planes of vertical canals reported by Blanks et al. (1972) and Robinson (1982), and with the angles of vertical eye muscles measured in this study and by Ezure and Graf (1984). 2. Maximal activation directions of 23 cells (21 burst-tonic and 2 tonic neurons) were determined from their responses during rotation in 4 or more different vertical planes. All cells showed sinusoidal gain curves and virtually constant phase values except near the null regions, suggesting that their responses were evoked primarily by canal inputs. Phase values of 5 cells near the null regions depended on the rotation plane, suggesting additional otolith inputs. We used a measurement error range of +/- 10 deg for calculating the maximal activation directions from the null regions of individual cells and the values of error ranges of null calculation. Of the 23, the maximal activation directions of 7 cells were outside the measurement error ranges of vertical eye muscle angles and within the ranges of vertical canal angles (class A), those of 5 cells were within the ranges of eye muscle angles and outside the ranges of vertical canal angles (class B), and those of the remaining 11 cells were in the overlapping ranges for both angles (class C). Even if only the cells in which 5 or more measurement points were taken to determine maximal activation directions (n = 15), the results were similar. During vertical rotation with the head orientation +60 deg off the pitch plane, dissociation of cell activity and vertical compensatory eye movement was observed in 5 cells in class A or C that had null angles near +45 deg. These results suggest that the cells in class A and B carried individual vertical canal and oculomotor signals, respectively, although it is difficult to tell for the majority of cells (class C) which signals they reflected. Some cells in class A and C were antidromically activated from the medial longitudinal fasciculus at the level of abducens nucleus, suggesting that the signals carried by these cells may be sent to the lower brainstem.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1990

Neuronal activity related to vertical eye movement in the region of the interstitial nucleus of Cajal in alert cats.

(1) Discharge characteristics of neurons in the region of the interstitial nucleus of Cajal (INC) were studied in alert cats during spontaneous or visually induced eye movement and sinusoidal vertical (pitch) rotation. Activity of a majority of cells (n = 68) was closely related to vertical eye position with or without bursting activity during on-direction saccades. They were called vertical burst-tonic (n = 62) and tonic (n = 6) neurons. Mean discharge rates for individual cells when the eye was near the primary position ranged from 35 to 133 (mean 75) spikes/s with a coefficient of variation (CV) ranging from 0.04 to 0.29 (mean 0.15). Average rate position curves were linear for the great majority of these cells with a mean slope of 3.9 +/- 1.2 SD spikes/s/deg. (2) The burst index was defined as the difference in discharge rate between maximal rate during an on-direction saccade and the tonic rate after the saccade. The values of mean burst index for individual cells ranged from 8 to 352 (mean 135) spikes/s. Tonic neurons had a burst index lower than 60 spikes/s and were distributed in the lower end of the continuous histogram, suggesting that burst-tonic and tonic neurons may be a continuous group with varying degrees of burst components. During off-direction saccades, a pause was not always observed, although discharge rate consistently decreased and pauses were seen when saccades were made further in the off-direction toward recruitment thresholds. Significant positive correlation was observed between average discharge rate during off- as well as on-direction saccades and tonic discharge rate after saccades for individual cells, which was not due to cats making saccades mainly from the primary position. (3) During pitch rotation at 0.11 Hz (+/- 10 deg), burst-tonic and tonic neurons had mean phase lag and gain of 128 (+/- 13 SD) deg and 4.2 (+/- 1.7 SD) spikes/s/deg/s2 relative to head acceleration. During pitch rotation of a wide frequency range (0.044-0.495 Hz), the values of phase lag were mostly constant (120-140 deg), while simultaneously recorded vertical VOR showed the mean phase lag of 178 deg. Vertical eye position sensitivity and pitch gain (re head position) showed significant positive correlation.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1987

Compound implant to project the nasal tip.

Use of a compound implant to project the nasal tip in cases of thick skin, a depressed or slightly descending tip, and a minimal bony hump is reported. This implant gives shape and projection, is easy to obtain, and is well tolerated by the organism. It is made of a strip of septal cartilage or silastic; the anterior end is covered by a portion of alar cartilage. There is a low percentage of complications with this technique.

Humans↗
PubMed1983

N4-aminocytidine, a nucleoside analog that has an exceptionally high mutagenic activity.

The reaction of cytidine with hydrazine to give N4-aminocytidine was greatly promoted by addition of a less-than-stoichiometric amount of bisulfite, and the product was isolated in a good yield. N4-Aminocytidine was strongly mutagenic to bacteria (Salmonella typhimurium TA100 and TA1535, and E. coli WP2 uvrA) and to phage (phi X174 am3). The activity did not require the presence of mammalian microsomal fraction in the system. The mutagenic potency of N4-aminocytidine in these systems was two orders of magnitude greater than that of N4-amino-2'-deoxycytidine, and more than two orders of magnitude greater than that of N4-hydroxycytidine. The greater activity of the riboside than the deoxyriboside was ascribed to the lack of deoxycytidine kinase in these cells. This compound may be useful as a powerful mutagen to induce a transition mutation in microorganisms.

Bacteriophage phi X 174↗
PubMed1983

N4-aminocytidine: formation, reactivity, and mutagenicity.

N4-Aminocytidine was readily formed on treatment of cytidine with hydrazine-bisulfite under mild conditions. This reaction can be carried out for cytosines in polynucleotids as well. The nucleoside N4-aminocytidine was strongly mutagenic to bacteria and phage. The transformation of cytosines in polynucleotides into N4-aminocytosines is a convenient method for generating reactive groups in the polymer.

Chemical Phenomena↗
PubMedDate not supplied

Biomechanics and classification of the cartilaginous structures to project the nasal tip.

The present paper is the long-term conclusion of our preliminary presentation at the 1992 ISAPS Congress (Guadalajara, Mexico). This is the result of 29 cadaver dissections of different ages and both sexes. We have observed that length, thickness, and resistance correlate with the possibility to project the nasal tip with the mere structure of the alar cartilage and its medial crurae. We also demonstrated the existence and antagonistic action of Pitanguy's ligament as well as the depressing ligament to project the nasal tip. In this study, besides focusing on classifying the medial crus according to its thickness, length, and resistance, which is already different from any previous classification, we also focused on its surgical utility, and its interaction with other anatomic elements, to achieve the desired projection. Clinically, we present a 12-year experience with 1653 cases operated under this premise.

Biomechanical Phenomena↗
PubMedDate not supplied

Severe optic disc edema without hydrocephalus in neurofibromatosis 2.

A 26-year-old man who had neurofibromatosis type-2 with symptoms of unexplained optic disc edema is reported. Magnetic resonance imaging (MRI) revealed bilateral acoustic schwannomas. Obstructive hydrocephalus, however, was not evident in spite of his severe disc edema and visual loss. After partial removal of the right acoustic schwannoma, symptoms of intracranial hypertension, such as vomiting and headache, developed and MRI demonstrated evidence of obstructive hydrocephalus. Placement of a ventricular-peritoneal shunt relieved the symptoms of intracranial hypertension, but visual acuity in his left eye was reduced to hand motion due to secondary optic atrophy. In patients with similar symptoms it is suggested that, in addition to tumor removal, early treatment to decrease intracranial pressure should be considered when visual function is progressively impaired by the symptoms of prolonged papilledema.

Adult↗